Variation in supramolecular organisation of the photosynthetic membrane of Rhodobacter sphaeroides induced by alteration of PufX

Kinga Sznee*, Lucy I. Crouch, Michael R. Jones, Jan P. Dekker, Raoul N. Frese

*Corresponding author for this work

Research output: Contribution to journalArticle (Academic Journal)

5 Citations (Scopus)

Abstract

In purple bacteria of the genus Rhodobacter (Rba.), an LH1 antenna complex surrounds the photochemical reaction centre (RC) with a PufX protein preventing the LH1 complex from completely encircling the RC. In membranes of Rba. sphaeroides, RC-LH1 complexes associate as dimers which in turn assemble into longer range ordered arrays. The present work uses linear dichroism (LD) and dark-minus-light difference LD (Delta LD) to probe the organisation of genetically altered RC-LH1 complexes in intact membranes. The data support previous proposals that Rba. capsulatus, and Rba. sphaeroides heterologously expressing the PufX protein from Rba. capsulatus, produce monomeric core complexes in membranes that lack long-range order. Similarly, Rba. sphaeroides with a point mutation in the Gly 51 residue of PufX, which is located on the membrane-periplasm interface, assembles mainly non-ordered RC-LH1 complexes that are most likely monomeric. All the Rba. sphaeroides membranes in their Delta LD spectra exhibited a spectral fingerprint of small degree of organisation implying the possibility of ordering influence of LH1, and leading to an important conclusion that PufX itself has no influence on ordering RC-LH1 complexes, as long-range order appears to be induced only through its role of configuring RC-LH1 complexes into dimers.

Original languageEnglish
Pages (from-to)243-256
Number of pages14
JournalPhotosynthesis Research
Volume119
Issue number1-2
Early online date7 Nov 2013
DOIs
Publication statusPublished - Feb 2014

Keywords

  • Photosynthesis
  • Rhodobacter sphaeroides
  • RC-LH1 complex
  • PufX
  • Linear dichroism
  • Supramolecular organisation
  • PIGMENT-PROTEIN COMPLEXES
  • LIGHT-HARVESTING MUTANTS
  • RC-LH1 CORE COMPLEX
  • LINEAR DICHROISM
  • REACTION CENTERS
  • PURPLE BACTERIA
  • RHODOPSEUDOMONAS-SPHAEROIDES
  • NATIVE ARCHITECTURE
  • STRUCTURAL-ANALYSIS
  • KEY ROLE

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